1. Ch 14 Fingerprints part 2

2. AFIS AFIS There was a manual system in place
Cumbersome system of storing, retrieving, & searching for prints
1970 now can classify and retrieve prints by computers
Very skeptical and hesitant at first
Automated fingerprint identification system
Automatic scanning devices that convert the image of a fingerprint into digital minutiae that contain data showing ridges at their points of termination (ridge endings) & the branching of ridges into 2 ridges (bifurcations)
There was a manual system in place
AFIS

3. AFIS More to it The trained expert
Relative position & orientation of minutiae are determined; computer stores each fingerprint in form of digitally recorded geometric pattern
Search algorithm determines degree of correlation
Can make thousands of fingerprint comparisons in a second
Makes final verification of print’s identity

4. AFIS How it operates Benefits $
A system within it filters out imperfections in latent print, enhances image, creates a graphic representation
Print is computer searched against file prints
Image of latent and match displayed side-by-side
Spend less time developing suspect lists
More time investigating suspects generated by computer
Need to be cautious of those prints not in system yet
Database that is created and managed, do have to pay to have access to it

5. Methods of detecting Visible prints Plastic prints
Latent (invisible prints)
Made by fingers touching surface after ridges been in contact with colored material
Ridge impressions left on soft material
Impressions caused by transfer of body perspiration or oils present on finger ridges

6. Detecting Latent Prints
Locating the invisible
Hard & nonabsorbent surfaces (glass, tile, etc) apply a powder or treat with Super Glue
Soft & porous surface (paper, cardboard, cloth) require treatment with chemicals
New technology - Reflected UV Imaging System - UV image converter helps to find latent prints w/o chemicals

7. Preservation of Developed Prints
Photograph
Taking print to lab
Must be taken once print has been visualized
Photos also need to be taken to provide overall view of print’s location w/ respect to crime scene
Option 1 wrap in cellophane and take whole thing
Option 2 use powder, then lift with tape and placed on labeled card